I don't really understand why different weights are required for different engines, climates, driving habits, etc... Could somebody tell me how you select the correct one?

I have a Kawasaki EX500 Ninja and my book says I can use a 10W40, 10W50, or a 20W50. I have no idea which one would be best to use. The bike only has 3000 miles on it, I live in NJ and this oil will be replaced before the summer is over. Also to keep this 3rd gen related, I also just built a new motor for my camaro, its a miniramed 350, around 10.2:1 compression with aluminum heads, and pushing anywhere from 400-500 horses. What oil do you suggest be run in that motor and why?

Thanks

 

I would use 10w30 or 10w40.You really wouldn't want anything thicker.The thinner the oil the most power can be obtained.I just would not use anything less than 10w30 for serious power.

 

i'd run 15w-50 or 20w-50 in the heat and somethnig like 5w-30 in cold weather

 

DA,

For the Ninja, I don't have a clue. I had a KZ-100 LTD back in 1978, and I used Shell 20W30 in that with good success (at least, for a Kawasaki - the timing chains still stretched). Since an air cooled engine can really stress and coke an engine oil, synthetic would be a prime choice. Those periodic high RPM excursions would also be a good reason for the extra protection.

For the SBC, you can use 5W-30 up to 60°F air temperature, but not beyond. At least that's what your owners manual should read, and the people who wrote that also built your engine. Some newer engines are designed for lower viscosity oils, with tighter clearances, lower net pressure per square inch on wear surfaces, and lower flow volume demands, but not your engine.

And be careful when considering viscosity numbers. The numeric ranges of CC²/sec (centistokes) for a given SAE viscosity index are so non-linear and have such different meanings for gear oils and crankcase oils, hot versus cold ratings, that the scale is a bit misleading, to say the least. Too bad the Society of Automotive Engineers (notice, they are NOT lubrication or chemical engineers) hasn't caught up with even the 1980's yet.

This link might make that a little more evident:
http://www.escape.ca/~dbrad/viscosity_c.htm

In the mean time, it's up to you to protect your assets, so don't rely on a 5W mineral oil for much more than an easy cold start. They don't provide much more than minimal protection at higher operating temperatures for more than a couple thousand miles, and begin breaking down quickly at higher temperatures.

Just as important, your engine also requires an oil change every 3,000 miles. Read the manual carefully and you'll see that, too. Mineral oils break down pretty quickly, and the additives that improve them break down even faster. After 3,000 miles, you really don't have much viscosity stability with multi grade mineral oils, and the additives are just about spent and begin burning up. The contaminants they produce will wipe out any cleaning they may have done if you don't change it regularly - the oil becomes it's own worst enemy.

Synthetics are a different matter entirely. They maintain viscosity across such a large temperature range that the SAE viscosity rating system is all but rendered completely meaningless with synthetics. The viscosity of most good PAO crankcase oils changes even less than that of water over a similar temperature range. They are naturally "multi grade" oils by the antiquated SAE viscosity scales, so they really require no fortifiers to maintain viscosity. The lack of fortifiers and viscosity improvers means there are fewer particles to break down and burn as the oil gets older, so there is almost no ash and soot created by synthetics as is common with mineral oils.

Synthetics probably clean better than anything, but are also more expensive. Synthetic blends might seem like a viable choice, but really have such a small percentage of synthetic base lubricant that they are not at all wqorth the extra cost. Once the engine is broken in and sealed, full synthetic should be safe. Pure synthetic lubes are the best for protection, lubrication under all conditions, and prevention of deposits. I have several older, high-mileage engines running on full synthetic with no problems, as long as you don't consider the cost as a problem.

Remember that the key will be the correct viscosity and regular changes, not necessarily the kind of lubricant base stock. It is far better to change mineral oil regularly than to stretch the change intervals on synthetics. If you built your engine with standard bearing clearances and piston skirt clearance, I'd go with a 15W or 20W50 PAO synthetic at ant temperature above 45°F. But that's just me. I use synthetic in everything. Even my 1984 B&S 5 HP lawnmower is still running on original rings and valves.

 

Vader and all others,

what would you think about using Amsoil Series 2000 0w30 100% synthetic oil in a high performance SBC? this is the best amsoil engine oil and is the "high performance" stuff. the only other grade is 20w50. that seems to thick to me. i am planning on using the 0w30. my car is driven from may to october only. i live in southwestern ontario. what do you think?

 

How hot does it get in Ontario? The 0w30 seems awfully thin for a daily driven summer car. You typically want a thicker oil in the summer because of how oil gets thinner when it is heated. If you start with a thin oil and it gets really hot, you're going to run into problems. In the winter, you want a thinner oil since you don't have to worry as much about the heat. This is what's good about multi-weight oils...they can handle changing weather.

 

i guess i'm old fashioned but i have a hard time accepting the idea of zero weight oil. on the other hand i'm not a chemist or oil engineeer either.

 

Thanks for the explainations. I guess I should have said that I got away from using mineral oils a long time ago. Synthetic is the only way to go for me and since Mobil 1 is sold in most parts stores thats what I use. It just confused me when I was reading the book on the motorcycle and it gave me 3 different weight options to run without any explainations as to which one should be used in different situations.

On a side note is it alright to go 6,000 miles between oil changes using synthetic oils, since they don't break down as fast as mineral oil?

 

As I mentioned earlier, most of our engines are not designed to use a lower viscosity lubricant, and don't have adequate bearing areas to distribute the load effectively over a large enough area to prevent shearing of the lubricant film surface. A 150 CID four cylinder with 3" diameter mains that are 2" wide would probably survive on a lower viscosity lubricant at a lower pressure, if the clearances were designed accordingly.

Like Ed mentioned, being a little older myself, I have a different philosophy. 0W oils are probably great for cooking "freedom" fries or 'shrooms, but not for engines. I'd rather expend a little more fuel pumping a more viscous lubricant through the engine and keep it longer than save a few pennies on gasoline and have to change bearings every 80,000 miles.

The coldest I ever experience is about -35 to -40°F. I've started engines that sat outside in that temperature overnight with 10W30 Mobil 1 in the sump, and get oil pressure immediately. Unless I got into the -50°F range, I wouldn't consider a 0W, and wouldn't feel comfortable once the engine warmed up to operating temperature. A Kawasaki engine might be designed with tighter bearing clearances and a wider surface area so they can survive 0W, but at higher ambient temperatures (where you would even WANT to ride a scooter) I would shy away from it.

As for extending drain intervals, it all depends on your driving. If you do a lot of what the factory calls "Normal Schedule" driving - long trips with no frequent starts and stops, no heavy loading, no dusty conditions, and kep the temperature fairly constant, you can safely extend the intervals. While it is true that synthetics maintain viscosity almost forever, they still gather contaminants. Most of us do what the factory calls "Severe Schedule" driving, which means we start and stop frequently, only run th eengien for an hour or less at a time, operate with heavy loads (from starting and stopping) and experience wide temperature swings in dusty conditions. For this reason, extending can be risky. I used to change synthetics at 3,000 mile intervals. Since moving to a more remote location and driving the extra highway mileage daily, I'm trying 4,000 mile intervals now. I'll let you know how well that works out when I tear down the next one for overhaul in about ten years.

Again, for your scooter engine, all I can suggest is to consult you manual and use the highest viscosity lubricant allowed at a particular temperature range. And don't forget to allow your engine to warm up and circulate a little oil before loading it.

BTW - I meant to say "KZ-1000 LTD" not "KZ-100" I don't think there was one of those available, even then.